Apparatus for tracing the profiles of devices



March 23, 1954 W. c. H. CROOK 2,672,690

APPARATUS FOR TRACING THE PROFILES OF DEVICES F'ild June 12, 1950 4Sheets-Sheet 1 lrwemiw MY/Lam C 52 (Mo/i MM K W- C. H. CROOK APPARATUSFOR TRACING THE PROFILES OF DEVICES Filed June 12, 1950 4 Sheets-Sheet 2[Mammy C (00% z 4 2; A Mom 537 March 23, 1954 w. c. H. CROOK 2,672,690

APPARATUS FOR TRACING THE PROFILES OF DEVICES Filed June 12, 1950 4Sheets-Sheet 3 Attorney March 23, 1954 w. c. H. CROOK APPARATUS FORTRACING THE PROFILES OF DEVICES Filed June 12, 1950 4 Sheets-Sheet 4 F Wg \E F/G. 3; j /S F2 o c g V I I) a l l QM,

A ,8, igue ntor W////am A. (5- 4 MM;

Altorney Patented Mar. 23, 1954 APPARATUS FOR TRACING THE PROFILES OFDEVICES William Charles Herbert land, assignor to D. London, England, aB

Crook, Hounslow, Eng- Napier & Son Limited,

ritish company Application June 12, 1950, Serial No. 167,651

Claims priority, application Great Britain June 27, 1949 1 Claim. 1

This invention relates to apparatus for tracing profiles upon a flatsurface for example for the purpose of determining the exact profile ofa part in a given plane, for checking the correctness of such profilesor for other purposes and is particularly but not exclusively applicableto apparatus for tracing a profile upon a plate so that the profile canbe optically projected on to a screen.

The object of the invention is to provide apparatus which will be simpleand accurate for tracing the profile of a part in a given plane upon afiat surface.

Apparatus for tracing a profile upon a flat surface according to thepresent invention comprises a base, hereinafter for convenience called ascribing block, movable upon a plane surface and carrying two verticallydisplaced points one of which (hereinafter called the profile-followingpoint) is arranged to engage and be moved over the surface of thearticle of which the profile in a plane is to be traced by a movement ofthe scribing block over the plane surface while such article is heldstationary, while the other constitutes a scribing point adapted totrace said profile on a fiat surface (hereinafter called the scribingsurface) parallel to the plane surface, the two points lying or beingcapable of being caused to lie on the same vertical line normal to theplane surface.

The scribing surface may be for example a glass plate coated on the faceon which the scribing point bears with lamp black or other thin opaquecoating in which a line representing the profile is made by the scribingpoint. It will be seen that the glass plate can then be used for theoptical projection, the line being transparent while the rest of thesurface is opaque.

Preferably a support for the scribing block is provided comprising amember on which the scribing block rests freely adapted to be gripped bythe hand and having a lower surface which rests upon the plane surfaceand an upper surface parallel to the lower surface on which the scribingblock rests so that the scribing block can be moved to cause movement ofthe profilefollowing point over the surface of which the profile is tobe traced by moving the support and yet the pressure with which the saidprofilefollowing point can be caused to bear upon the profiled surfaceis limited to that represented by the friction between the scribingblock and its support.

Such a support may resemble a bobbin, that is to say. may havecomparatively large diameter ends resembling flanges on which the upperand lower surfaces are formed and a small diameter intermediate part tobe gripped by the hand.

The means for supporting the article of which the profile is to betraced may vary but preferably are arranged to support the article upona vertical axis and include means for moving the article bodily alongthe said vertical axis thus enabling the profile of the article inhorizontal planes at various vertical positions to be traced.

In any case the profile following point is preferably adjustable in ahorizontal plane relatively to the scribing block so as to enable it tobe brought exactly on to the vertical line containing the scribingpoint, while the scribing point, which may also be verticallyadjustable, is conveniently carried on a light leaf spring which whencorrectly adjusted maintains it in contact with the scribing surface.

The invention may be carried into practice in various ways but oneconstruction according to the invention is illustrated by way of examplein the accompanying drawings, in which Figure 1 is a side elevation ofthe invention as arranged for tracing the profile of a turbine blade;and Fig. 1 is a side elevation of appara tus for supporting the turbineblade and scribing surface; Figures 1 and 1 together showing thecomplete apparatus,

Figure 2 is a plan view of paratus shown in Figure 1,

Figure 3 is a side elevation on an enlarged scale and partly in sectionon the line 3-3 of Figure 2, and

Figure 4 is a cross section on the line 4-4 of Figure 2.

The apparatus illustrated is used upon the accurate surface of a faceplate indicated at A and comprises adjustable supporting mechanism forsupporting the article of which the profile is to be traced and scribingapparatus.

The adjustable supporting mechanism comprises a base B having three feetin the form of metal beds B which rest upon the surface of the faceplate A, one or more of the feet conveniently being adjustable in knownmanner to ensure that the base B lies exactly parallel to the surface ofthe face plate A. Rigidly supported upon the base B is a vertical pillarC of hexagonal cross section, this pillar being hollow and havingmounted thereon a slide indicated generally at D which can movevertically upon but not rotate relatively to the pillar and isconveniently counter-weighted by a weight E freely disposed within thepillar and connected to the slide D one part of the ap- 3 by a flexiblecable or strip E passing over a pulley E at the upper end of the pillarC.

The slide D is accurately located with respect to the pillar by means oftwo plates D secured respectively to its upper and lower ends and havinginner surfaces which conform exactly to the three adjacent faces of thehexagonal pillar C as shown most clearly in Figures 2 and 3, theengaging surfaces of the plates D and. of the pillar being held in closecontact by two rollers F mounted to rotate on horizontal pins F whichare carried by opposite ends of a pressure plate F located in the boreof the slide D as shown in Figure 3 and acted upon by two compressionsprings F located in housings in the slide D.

Thus it will be seen that the rollers F are pressed by the springs Finto engagement with the face of the pillar C remote from the plates Dand thus serve to hold the plates D in close engagement with theassociated surfaces of the pillar while permitting the slide D as awhole to move vertically upon the pillar. V

A locking screw G passes through a screwthreaded bore in the slide D asshown in Figures 2 and 3 and passes freely through the plate P so as toact upon the pillar C and thus enable the slide D to be lockedfrictionally in any desired vertical position upon the pillar.

The slide D is provided with adjusting mechanism for. moving itvertically upon the pillar C comprising a rack H'rigidly secured to thepillar and engaged by a pinion H mounted upon a spindle H supported in abearing H carried in a bore in the slide D as best shown in Figure e,the

bearing. H conveniently being secured in position by two set screws HThe spindle 1-1 car ries a second gear wheel H and is also provided withan extension H of reduced diameter forming a spindle on which isrotatably mounted by means of abearing. H, a, hand wheel H8 having ahandle H Supported on a fixed spindle (not shown) carried by the. slideD is a hollow lay shaft J carrying two gear wheels J J one of whichmeshes with. the gear wheel H while the other meshes with; a gear wheelJ 3 formed or mounted on the hand wheel H It will thus be seen that thegearing above described constitutes a transmission train between thehand wheel H and the gear wheel H by which the latter gear wheel can berotated and thus act through the rack H to. cause vertical movement ofthe slide D upon the pillar C. The ratio of. the transmission train issuch as to provide a comparatively small degree of vertical movement ofthe slide D for one revolution of the hand wheel 1-1 In the arrangementshown the hand wheel carries a scale indicated at K upon its rim withwhich cooperates a pointer K rigidly secured to a flanged member K whichis secured to the slide D and serves, with a cooperating flanged memberK on which the scale K is formed, to enclose the gearing J J- J H In oneexample the scale K is such that each division represents vertical,movement oftheslide D by of an inch. I

The slide D carries a laterally projecting platform D on which isrigidly mounted. a support for the article of. which the profile is tobe investigated, which in the example shown isa turbine blade L. Theblade support comprises a base M secured to the platform D and carryinga pillar M Mounted upon the base in an arm M arranged to pivot about ahorizontal axis M while adjustably secured to the pillar M is a slide Mhaving, pivoted toitinan adjustable arrangement manner an arm M the armsM and M carrying at their ends chuck or gripping members N, N formed,for example with hard rubber inserts, to grip respectively the upper andlower. ends of the blade L or projections: L thereon. The arm M isspring loaded and has associated with it adjusting mechanism indicatedgenerally at M by which its position can be adjusted, while the upperarm M5 is provided with means indicated at M by which it can be causedto rock about the thin section indicated at M so as to hold the blade Lin place by compression between the members N and N It will thus be seenthat by vertical adjustment of the slide D and individual adjustment ofthe arms M and M the blade L can be supported in any desired verticalposition within the limits of adjustment.

Projecting from the upper end of the pillar C and rigidly secured toiitis a vertical rod 0 on which is adjustably mounted a laterally extendingarm 0 the arm being secured to the rodO frictionally by means of afriction grip device having an adjustment screw 0 The outer end of thearm 0 hasrigidly but adjustably secured to it a platform 0 having springclips 0* by which a glass or like plate P constituting the scribingsurface and supported thereon can be held frictionally from movementthereon, the being such that the plate P lies vertically over the bladeL.

The scribing apparatus comprises a bobbinlilre support Q with the lowerface of the lower flange (53 and the upper face of the upper flange Qtruly parallel, forming a base supporting member. lower face of thelower flange Q rests upon the surface of. the face plateA while mountedto slide freely upon the upper face of the upper flange is a scribingblock or base R. Projecting laterally from the scribing. block R is asupport R carrying an adjustable chuck R2 carrying a pointed profilefollowing pin R The support R is adjustable in a horizontal plane abouta vertical supporting pin R relatively to the scribing block, while thechuck R is adjusts able radially with respect to the pin R relatively tothe support R so that the point of the pin R. can be caused to lie at aprecise selected position in a horizontal. plane relatively to the baseR.

Supported from the base It is a post S the upper end of which hasrigidly secured to it a supporting block S to which is secured the innerend of a spring arm S in the form of a leaf spring, the outer end ofwhich has secured to it and projecting downwardly from it a scribingpoint T., lhe spring arm S has secured to it adjacent to its inner end alug S acted upon; by an adjacent screw 5 whereby the spring arms 5; canbe flexed to adjust the vertical position of rest of the scribing pointT.

The apparatus when adjusted for use is adjusted so that the scribingpoint T lies directly vertically above the point of the pin Rthe-scribing point T being adjusted so that it bears lightly upon theupper surface of the plate P which will generally be a glass platehaving a surfacing of lamp black or other thin opaque substance whichcan be removed in a fine line by movement of the scribing point T'overit.

In operation with the blade L mounted on the blade support, the slide Dis adjusted until the horizontal plane in which the point of the pin Rlies cuts the blade L at the point in its. length at which the. crosssectional profile is to be investigated. The bobbin like base supportingmember Q is now gripped and is moved so as to cause the scribing blockor base R and hence the point R to pass in the said plane over thesurface of the blade L. It will be seen that in such passage the profileof the blade will be accurately traced by the scribing point T upon theglass plate P and moreover that the pressure with which the point Rbears upon the blade cannot exceed that represented by the frictionbetween the upper face f the base supporting member Q and the scribingblock or base B so that errors which might otherwise occur due to thepoint R being pressed against the blade L with excessive pressure areavoided.

In practice the procedure will usually be to trace the profile of thetransverse cross section of the blade either on the same plate P or ontwo or more separate plates at a selected number of predetermined pointsin the length of the blade so as to determine the accuracy or otherwiseof the profile of the blade as a whole.

What I claim is:

Apparatus for tracing a rofile on a flat surface comprising a basesupporting member adapted to be moved by hand over a plane horizontalsurface and having a lower surface which rests freely and slidably uponthe plane horizontal surface and an upper surface parallel to the lowersurface, the said base supporting member resembling in shape a bobbin byhaving relatively large diameter ends on which the upper and lowersurfaces are formed, and an intermediate part of smaller diametersuitable for being gripped by the hand of an operator, a base formedwith a lower surface which rests freely and slidably on the uppersurface of the base supporting member, two vertically displaced pointscarried by the base, one of the points being arranged to engage and moveover the surface of an article of which the profile is to be traced in aplane, while the other point constitutes a scribing point arranged totrace said profile on a horizontal fiat surface, the two points beingarranged to lie on the same vertical line.

WILLIAM CHARLES HERBERT CROOK.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,352,695 Clausing et al. July 4, 1944 2,368,853 Levaggi Feb.6, 1945 2,468,995 Morrison May 3, 1949 FOREIGN PATENTS Number CountryDate 47,672 Sweden Sept. 1, 1920 492,948 Germany Mar. 1, 1930 176,006Switzerland June 1, 1935 616,759 Great Britain Jan. 26, 1949 616,970Great Britain Jan. 31, 1949

